Joking aside, I don't have full access from home, but using Ancestry's search feature gives the following "possible", unfortunately LDS doesn't carry this Census so I cannot offer further detail.

1851 Wales Census;

Thomas HILLMAN aged 30 so born about 1821,
Residing Abergavenny District, MONMOUTHSHIRE.

There are only six other Hillmans listed in this census and I don't think any are in the same household.

So no distance from the Forest and perhaps within our family's travels. ??

Please can someone take a look and glean further details, following link may help find it, many thanks.
http://search.ancestry.co.uk/cgi-bin/sse.dll?db=uki1851wales&so=2&pcat=CEN_1850...